These are the elements of a dramatic spate of recalls plaguing the makers of Tylenol, and keeping store shelves relatively bare of the brand’s once-robust suite of products.

Drug stores, pharmacy sections and supermarkets are running low on Tylenol after years of these recalls, leaving consumers to weather the summer cold season without an abundance of the drug that’s become synonymous with acetaminophen.

Instead, a platoon of private brands have been strategically placed in the pain-relief aisle, as stores leap to fill the void with their own products.

Sometimes, this can make for an irked customer who’s brand-loyal, or who has been told by a doctor to take Tylenol for mild pain and fever.

“They’re a little disappointed,” said Larry Jones, store manager at a Rite Aid drug store in East Sacramento. “They are not happy about it, but I say, ‘What can you do?’ Then they get mad.”

While offering few details, Tylenol’s makers are vowing to return the company’s products to the shelves as soon as possible. They made a point of noting that the recalls were voluntary, and that none of the recalled drugs had posed serious health risks. But at this point, with millions of vials recalled, the bulk of the Tylenol line is unavailable to consumers.

The story behind the low stocks of Tylenol is also the story of how its maker, Johnson (ampersand) Johnson, found itself overwhelmed by quality control problems known to the U.S. Food and Drug Administration.

Shelves have been partly or mostly bare of the Tylenol products since 2009, when the FDA pressed the 125-year-old company to start voluntary recalls amid growing complaints about a musty, moldy odor in many Tylenol products.

The FDA lacks the authority to order mandatory recalls outright, but it could threaten court action against pharmaceutical firms if voluntary recalls were not launched.

The troubles began in 2008, when Johnson (ampersand) Johnson was slow to identify the problem behind the moldy odor, prompting criticism from the FDA.

It turned out to be airborne contamination from a chemical called 2,4,6-Tribromoanisole, or TBA, a pesticide and wood preservative used to treat wooden pallets. The pallets, at the company’s manufacturing plant in Puerto Rico, held Tylenol packaging materials for storage and transport.

Under the stern eye of the FDA, the firm launched what would be the first of a series of rolling recalls. The primary concern was Tylenol tainted by TBA, but there were also cases of over-the-counter medicines containing minute pieces of wood and metal, a batch of raw materials contaminated by the infectious bacteria burkholderia cepacia, Tylenol formulas for children that were too potent and Motrin tablets that were basically impotent.

There were 26 recalls from 2009 to May 17, 2012, many of them affecting multiple products. Details are posted on the website of McNeil Healthcare LLC, a subsidiary of Johnson (ampersand) Johnson. None of the recalls involved life-threatening conditions, the FDA and Johnson (ampersand) Johnson said.

The rolling recalls targeted not just Tylenol but a host of other Johnson (ampersand) Johnson product lines as well. They included Rolaids, Motrin, Benadryl, Imodium, Sudafed PE, Aveeno, Zyrtec, St. Joseph’s Children’s Aspirin and Simply Sleep brands.

Congressional hearings in 2010 put both FDA officials and Johnson (ampersand) Johnson executives in the hot seat. The FDA ultimately stepped up its quality-control oversight. Of the four manufacturing facilities making the drugs, three ended up seized by court order by the FDA. The FDA closed down the most problematic plant, in Fort Washington, Pa., and company officials are unable to say when it may reopen.

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All of this explains why, today, pain-relief aisles are bereft of the once-ubiquitous family of Tylenol brands — and some other prominent brands as well.

But if you ask your pharmacist, store manager or attendant what’s behind the shortage, you can pretty much count on getting a general, rather than specific, answer.

“They don’t tell us anything except there’s a recall and to take the products off the shelves,” said Jones. “Then we get no shipments for months.”

Other pharmacy employees in Sacramento said they hadn’t seen a Tylenol shipment for up to a year.

Johnson (ampersand) Johnson spokeswoman Jodie Wertheim released this statement in an email:

“You may have noticed that some of our Tylenol and other McNeil products have been hard to find. We are in the process of returning to market certain products that were impacted by recalls.”

At stores, however, there’s still this confusing matter of a lack of widespread consumer awareness about the recalls and a lack of clarity over when exactly the missing products will be available.

Doctors still advise patients to take Tylenol, perhaps meaning that any similar acetaminophen product will do. Patients, consumers or caregivers still go in search of the brand name.

Now, the company that 30 years ago famously survived a cluster of cyanide poisonings in a Chicago tampering case faces an even greater marketing challenge. After three years of erratic or halted product shipments, Johnson (ampersand) Johnson may have permanently lost some customers to the cheaper private store labels.

“They say the consumer is a fickle animal,” said Herman Saftlas, a pharmaceutical stock analyst for Standard (ampersand) Poor’s Capital IQ. “If they leave the product and are happy with the replacement, they may not come back.”